S-series with 24 frets?
I know that Machinehead have fitted 24 fret Ibanez necks to both Strats and Sabers with the OLD style neck joint.
One thing I might suggest, if you can live without the neck pickup, or are prepared to rout some big holes for a new pickup position, is a fretboard swap. I think Kevan did a tutorial posted on Universal JEMs (bcalvert's site) about lifting and replacing a fretboard. So you could take the 22 fretter off the Saber's neck and fit a 24 fret board.
I know Machinehead will fit a new board to an existing neck for a couple of hundred quid and they might be willing to undertake this task.
N.B. I'm not advertising my fave shop as such, just saying that they and other capable shops can do this sort of thing.
(Edited by jono at 9:20 am on Jan. 31, 2002)